I have an large, old (1880) house with an attic that gets really hot in the summer. As we have no air conditioning (we live in MI), I'm thinking about getting an attic fan or whole house fan.

The roof is 12/12 pitch all around, but dead in the center there is an 8'x8' flat area with a 3'x3' hatch (plywood nailed down, currently) to get out onto the roof. Should I use that hatch to vent my attic?

The attic also has hardwood floors (in somewhat bad shape) and 3 old windows that don't open or open poorly. Should I just get a window fan or maybe a gable fan?

There isn't much ventilation in the attic that I can see except some critters get in and out, so I think there must be some 'natural ventilation' . Should I add some other vents as well, or will the 'leaky old house' aspect of it be enough?

Since I don't have AC and don't have to worry about drawing up air conditioned air up into the attic, would a whole house fan be better?